Koepka’s second U.S. Open win even more exceptional than his first

Brooks Koepka’s performance in his second U.S. Open victory at Shinnecock Hills in June was even more dominant than his 2017 victory.

Koepka compiled a Z Score of -2.42 in overcoming the Shinnecock challenge, fractionally more dominant than his winning -2.24 Z Score at Erin Hills in 2017.

In strokes, Koepka’s winning margin in the 2018 Open was just one stroke over Tommy Fleetwood. He won the 2017 tournament by four strokes. But the field average of the players who completed four rounds at Shinnecock was 292.35 strokes, significantly higher than the 288.12 field average for those completing four rounds at Erin Hills in 2017. The 2018 field was also much more tightly bunched, with a performance standard deviation of 4.69 strokes. The standard deviation of the field average in 2017 was 7.21 strokes, demonstrating a much more spread-out field. Both of those factors made Koepka’s 2018 performance more exceptional.

Even so, Koepka’s Z Score does not measure up with the all-time top 25 U.S. Open performances. Attaining that plateau would have required a Z Score of -2.56, a standard last attained in the Open by Martin Kaymer in 2014. Koepka’s Z Score is the best in the U.S. Open since Kaymer’s -2.81.

Here are the 10 most exceptional U.S. Open performances in history based on winning Z Score: